5
मेरे कार्यक्रम इस (main.c) की तरह है:Malloc, स्ट्रिंग संकेत दिए गए, और वेलग्रिंड
#include <stdlib.h>
#include <stdio.h>
void main(){
char *first="hello ";
char *second="world!";
char *seq=(char *)malloc((strlen(first)+1)*sizeof(char));
strcat(strcpy(seq,first),second);
printf("%s\n",seq);
free(seq);
}
और मैं उपकरण valgrind साथ डिबग, यह कहा कि ($: valgrind --tool = Memcheck --leak की जांच = पूर्ण --track-मूल = हाँ ./main):
==5118== Memcheck, a memory error detector.
==5118== Copyright (C) 2002-2008, and GNU GPL'd, by Julian Seward et al.
==5118== Using LibVEX rev 1884, a library for dynamic binary translation.
==5118== Copyright (C) 2004-2008, and GNU GPL'd, by OpenWorks LLP.
==5118== Using valgrind-3.4.1, a dynamic binary instrumentation framework.
==5118== Copyright (C) 2000-2008, and GNU GPL'd, by Julian Seward et al.
==5118== For more details, rerun with: -v
==5118==
==5118== Invalid write of size 1
==5118== at 0x402575B: strcat (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==5118== by 0x80484EB: main (main.c:7)
==5118== Address 0x418a02f is 0 bytes after a block of size 7 alloc'd
==5118== at 0x402522D: malloc (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==5118== by 0x80484C3: main (main.c:6)
==5118==
==5118== Invalid write of size 1
==5118== at 0x4025777: strcat (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==5118== by 0x80484EB: main (main.c:7)
==5118== Address 0x418a034 is 5 bytes after a block of size 7 alloc'd
==5118== at 0x402522D: malloc (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==5118== by 0x80484C3: main (main.c:6)
==5118==
==5118== Invalid read of size 1
==5118== at 0x4025963: strlen (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==5118== by 0x40A0FA4: puts (in /lib/libc-2.10.1.so)
==5118== by 0x80484F7: main (main.c:8)
==5118== Address 0x418a02f is 0 bytes after a block of size 7 alloc'd
==5118== at 0x402522D: malloc (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==5118== by 0x80484C3: main (main.c:6)
==5118==
==5118== Invalid read of size 1
==5118== at 0x40ACEFE: _IO_default_xsputn (in /lib/libc-2.10.1.so)
==5118== by 0x40AA3D0: [email protected]@GLIBC_2.1 (in /lib/libc-2.10.1.so)
==5118== by 0x40A1020: puts (in /lib/libc-2.10.1.so)
==5118== by 0x80484F7: main (main.c:8)
==5118== Address 0x418a02f is 0 bytes after a block of size 7 alloc'd
==5118== at 0x402522D: malloc (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==5118== by 0x80484C3: main (main.c:6)
hello world!
==5118==
==5118== ERROR SUMMARY: 17 errors from 4 contexts (suppressed: 13 from 1)
==5118== malloc/free: in use at exit: 7 bytes in 1 blocks.
==5118== malloc/free: 1 allocs, 0 frees, 7 bytes allocated.
==5118== For counts of detected errors, rerun with: -v
==5118== searching for pointers to 1 not-freed blocks.
==5118== checked 47,492 bytes.
==5118==
==5118==
==5118== 7 bytes in 1 blocks are definitely lost in loss record 1 of 1
==5118== at 0x402522D: malloc (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==5118== by 0x80484C3: main (main.c:6)
==5118==
==5118== LEAK SUMMARY:
==5118== definitely lost: 7 bytes in 1 blocks.
==5118== possibly lost: 0 bytes in 0 blocks.
==5118== still reachable: 0 bytes in 0 blocks.
==5118== suppressed: 0 bytes in 0 blocks.
मुझे बता सकते हैं कौन क्यों और कैसे इसे ठीक करने के लिए।
सी में 'malloc()' के वापसी मूल्य को डालने की कोई आवश्यकता नहीं है; भी, 'sizeof (char) 'हमेशा' 1' – Christoph